For Ubuntu 13.04, all alphas and the first beta release have been dropped from the release schedule, so Raring Ringtail will have only one beta version and obviously, the final stable release.

Nicholas Skaggs, the Canonical QA Community Coordinator, mentions in a blog post that instead of the old milestones, a bi-weekly testing process will be used throughout the development cycle. He also mentions that the daily ISOs will continue to be published as usual and they will be automatically 'smoke' tested to make sure there are no more broken installers on the published images.

Further more, the freezes (for instance, when the Feature Freeze takes place, the developers stop introducing new features or packages and concentrate on fixing bugs only) have been moved back a few weeks so the development will continue until late in the release cycle.

The Ubuntu 13.04 Raring Ringtail schedule should now look like this:

March 28th: beta release

April 25th: final Ubuntu 13.04 release

These changes will only affect the main Ubuntu flavor (with Unity), while the other flavors like Xubuntu, Kubuntu, etc., will have complete control over their releases so we might see different release schedules for each Ubuntu flavor.